The present invention relates to an IT terminal, more specifically to a portable type IT terminal having a built-in audio function and a method of identifying plural kinds of audio equipment to be connected to a communized jack interface.
As a result of technical development of key technologies such as communication technology and semiconductor technology, compact and high performance portable IT (Information Technology) terminals such as notebook type PCs (Personal Computers) and PDA (Personal Digital Assistants) have been developed and are rapidly popularized. By the use of such IT terminal, information such as various data and the like stored in an internal memory is available to a user by easily reading out of the memory as well as making various information such as, for example, desired music available by transmitting to a computer in an office or at home by way of a wireless communication network or by downloading through an internet or the like. IT terminals having such audio function are increasingly popularized.
For example, in a notebook type PC, since the physical size is rather large, it has various built-in audio plugs such as a headphone, a microphone, a line-in and the like. It is therefore possible to install mating plural jack interfaces and corresponding circuitries. However, in a portable IT terminal such as a PDA or the like that is considerably smaller than the notebook type PC, it has strict physical restriction and is typical to install only a single interface such as a headphone or a microphone.
Conventional technologies relating to or associated with IT terminals are disclosed in some technical documents. Disclosed is an audio signal processing apparatus and a portable telephone equipped with a stereo headphone and a microphone to cope with stereo audio processing by distinguishing them (refer to, for example, JP2002-101491 A1). Also disclosed are a method and an apparatus for signal path switching for a portable telephone equipped with a plug detector for detecting whether the plug connected to a jack terminal for earphone microphone is a plug for earphone microphone or a plug for stereo headphone (refer to, for example, JP2002-141980 A1).
Also disclosed is an input/output circuit for audio equipment in which a common connection jack for headphone and for microphone is provided so as to be used in common by switching after distinguishing the connected headphone or microphone (refer to, for example, JP48-163686 A1). Moreover, in an audio equipment such as a tape recorder or the like, disclosed is a signal input/output circuit for audio equipment for achieving compact design by using a single connection jack for both of a connection jack for stereo headphone and a connection jack for monaural microphone (refer to, for example, JP49-307990A1).
As described hereinabove, a conventional portable IT terminal (such as a notebook PC, a PDA, etc.) is equipped with a jack interface for an optional headphone or a microphone. A notebook PC has a sufficient physical size to provide a plurality of jack interfaces for a headphone, a microphone and the like to be used in combination with various audio equipment and independent circuitries therefor. However, a portable IT terminal such as a PDA or the like is smaller and thus it is physically difficult to provide a plurality of jack interfaces. It is therefore typical to provide only a single jack interface having a single function for a headphone or a microphone.
Nevertheless, as a result of advancement of multi-media functions and a solution system even in a compact portable IT terminal, there are needs for adapting various audio equipments such as a headphone, an earphone microphone, a stereo microphone, etc. Accordingly, while maintaining compact design of a portable IT terminal, it is necessary to provide a multi-function type jack interface and circuitries capable of handling such various audio equipments and software capable of properly setting a speaker volume and microphone gain depending on the audio equipment connected thereto. Unfortunately, however, conventional technologies fail to comfortably satisfy the needs.